1. Field of the Invention
The invention relates to a measuring mechanism for wide-angle moving coil systems, consisting of a mount with a movable part, an inner and an outer pole ring and one or two magnets. The invention relates further to a method for assembling the parts.
2. Background of the Prior Art
With known measuring mechanisms of the initially described type, the movable part of the measuring mechanism can be mounted and balanced only inside the magnetic system. These operations, however, are a very great waste of time and impose a great burden on assembly personnel. Because of the simultaneous incorporation of heavy and highly sensitive parts in a single operating step, a further potential danger is that of damaging sensitive measuring mechanism pivots and bearings. To mechanize and/or economize on these operations is practically impossible.
A further drawback of these known measuring mechanisms is that the pole rings and magnets have to be screwed or bonded together in an expensive way. Because it is very expensive to insert bores or the like into permanent magnets, the screw coupling is extremely expensive.
A further difficult requirement is that the parts need to be arranged concentrically and for this purpose require adjustment. This operating stage is necessary because otherwise the scalar linearity of the measuring mechanism cannot be guaranteed. A mutual bonding of the parts requires considerably complex apparatus. Despite this complexity, however, usually the desired degree of concentricity is not reached and, further, cannot be corrected, which has detrimental effects. The above noted costs of final assembly of the measuring mechanism and its final adjustment must also be considered.
An object of the invention then is to provide a measuring mechanism for wide-angle moving coil systems, where together with an extensive reduction in production and assembly costs, the required concentricity of magnetic system components and, accordingly, the desired linearity of measuring mechanism readouts can be accomplished. Specific fabrication aims are a simplification of laborious assembly operations and avoidance of adjusting operations. These problems arise for the above noted wide-angle moving coil systems, where the pointer, and therewith the moving coil frame, must sweep a wide angle e.g., of 250.degree.. In this case, the discussed problems of concentricity and linearity are substantially more difficult to manage than with so-called 90.degree.-instruments, i.e., where moving coil frame and pointer sweeper only a 90.degree.-angle, and where part of the negative eccentricity effects produced on instrument linearity are cancelled. This is so because the coil at diametrically opposed positions dips twice into the magnetic field. But with so-called 250.degree. or wide-angle systems--in contrast with 90.degree.-systems--there is no compensation for momentary deviation effective at both coil sides.